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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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344                                ALASKAN GLACIER STUDIES
forming pronounced, saw-tooth ridges at the borders of several of the barren zones, as already described.
The only well defined moraines above sea level recognized in this region are the cres-centic moraines in front of Baker and Roaring Glaciers and fragments of terminal moraine in front of Serpentine (Kg, 45) and Barry Glaciers (PI. CXL). A valley on the eastern side of Barry Arm contains Lake Cecelia, which Mendenhall described in 18981 as held in by "a low morainic ridge" which "may be the terminal of the glacier now in retreat at the head of the valley, or may be a lateral left by a tributary ice stream which enters from the east." In other places the terminal moraines either have been cut away by streams or were not built because the glaciers terminated in the sea, or were retreating rapidly.
Outwash. The areas of outwash plain have already been described, the one in front of Toboggan Glacier (Kg. 48) being the largest. There are similar areas near the Serpentine and Baker Glaciers, on the western side of the terminal moraine which was being built by Barry Glacier in 1898-99, and in front of Dirty, Pigot, Bettela, and several of the smaller ice tongues.
Submerged Moraines. Of the terminal moraines below sea level the most conspicuous one is a continuation of one on the land. It occupies the position of Barry Glacier in 1898 and 1899, has a roughly crescentic form (PI. CXL) and rises to sea level in three localities. At all other points it lies within from 96 to 234 feet of the surface, with deeper water on both the inner and outer sides. Opposite Pt. Doran, where this terminal moraine rises to the level of the sea, moderate-sized banks occur at low tide, the one nearest the point being about 1200 feet long, and made of till and bowlders. It is covered at half tide. Besides these three banks there is a shoal in the middle of Harriman Fiord, where the water is only 18 feet deep at low tide; and near the large isolated ice mass, on the western side of Barry Arm, a projecting peninsula 1800 feet long is exposed at low tide, continuing the belt of terminal moraine above sea level. The Barry Arm portion of this crescentic moraine nowhere rises to sea level, the water upon it being 120 to 234 feet deep. Between tin's submerged terminal moraine and the front of Barry Glacier, the water increases rapidly in depth, being 426 feet deep half a mile from the ice front, and increasing in depth at about the same rate westward up Harriman Fiord and southward down Barry Arm.
The submerged continuation of the terminal moraine of Serpentine Glacier is shown in Fig. 45. It is a rocky bar, practically all exposed at low tide, and rising 39 feet or more above the bottom of the cove in which the glacier now ends.
Another shoal area in Harriman Fiord, which might be interpreted either as terminal moraine below sea level or as rock-swell due to differential glacial erosion, is at the junction of the inlets which lead to Surprise and Harriman Glaciers (Fig. 50). Here there is an irregularity of the fiord bottom rising nearly 300 feet above the bottom of the fiord to the south, the crest of it being 90 feet below sea level in mid-fiord. If morainic, it was built by Harriman Glacier at a time when it extended 6 miles farther north. Icebergs strand upon this shoal more than J mile offshore on the western side of the fiord, suggesting a moraine bar here.
North of this, opposite Baker Glacier, the water is 120 to 174 feet in depth, being
i Mendenhall, W. C., 20th Ann. Rept., U. S. Geol. Survey, Part VII, 1900, p. 325.